Electrical wires having an aluminum or aluminum-alloy (hereinafter referred to as an aluminum or the like) core wires have been used for power applications such as electrical lines from power plants. In recent years, applications of electronic wires having the same kind of core wires to wires in vehicles to reduce weights of the vehicles are expected.
The wires used for such a purpose have bare parts of core wires located at ends of the wires and from which sheath are stripped off. Wire barrel of terminals are crimped onto ends of the respective core wires, and the terminals are connected to terminals of counter parts.
A metal used for each core wire has characteristics that a metal oxide layer having insulating properties is easily formed on a surface of the core wire. Therefore, a high contact resistance may be present between the core wire and the terminal. Aluminum oxide layers that are very hard are easily formed on surfaces of core wires made of aluminum or the like. As a result, a high contact resistance appears between each core wire and a terminal, which is a problem. One method to reduce the contact resistance between the core wire and the terminal is that a wire barrel having serration grooves is crimped onto the core wire.
When the terminal having the serration grooves is crimped on to the core wire, edges of the serration grooves rub against the metal oxide layer on the surface of the core wire. As a result, the metal oxide layer is cracked and a new metal surface of the core wire emerges. The wire barrel of the terminal is in contact with the new metal surface. Therefore, the contact resistance between the core wire and the terminal can be reduced.    Patent Document 1: Japanese Patent Application Publication No. 10-125362.